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This study profiles ceramides extracted from visceral and subcutaneous adipose tissue of human subjects by liquid chromatography-mass spectrometry to determine a correlation with status of diabetes and gender.Samples of visceral and abdominal wall subcutaneous adipose tissue (n = 36 and n = 31, respectively) were taken during laparoscopic surgery from 36 patients (14 nondiabetic, 22 diabetic and prediabetic) undergoing bariatric surgery with a body mass index (BMI)35 kg/mAfter logarithm 2 conversion, paired analysis of visceral to subcutaneous tissue showed differential accumulation of Cer(d18:1/16:0), Cer(d18:1/18:0), and Cer(d18:1/24:1) in visceral tissue of prediabetic/diabetic female subjects, but not in males. Within-tissue analysis showed higher mean levels of ceramide species linked to insulin resistance, such as Cer(d18:1/18:0) and Cer(d18:1/16:0), in visceral tissue of prediabetic/diabetic patients compared with nondiabetic subjects and higher content of Cer(d18:1/14:0) in subcutaneous tissue of insulin-resistant female patients compared with prediabetic/diabetic males. Statistically significant differences in mean levels of ceramide species between insulin-resistant African American and insulin-resistant Caucasian patients were not evident in visceral or subcutaneous tissue.Analysis of ceramides is important for developing a better understanding of biological processes underlying type 2 diabetes, metabolic syndrome, and obesity. Knowledge of the accumulated ceramides/dihydroceramides may reflect on the prelipolytic state that leads the lipotoxic phase of insulin resistance and may shed light on the predisposition to insulin resistance by gender.目的: 采用液相色谱-质谱分析从受试者内脏和皮下脂肪组织中提取的神经酰胺, 以确定神经酰胺与糖尿病状态和性别的相关性。 方法: 在腹腔镜手术中采集36例内脏和31例腹壁皮下脂肪组织标本, 这些标本来自36位患者, 其中14位非糖尿病, 22例糖尿病及糖尿病前期患者, 体重指数35 kg/m

Designing hydrogels for controlled drug delivery remains a big challenge. We developed a calcium polyphosphate hydrogel (CPP) as matrix for delivery of vancomycin (VCM) and erythromycin (EM) by unique ionic binding and physical wrapping. In this continuing study, we investigated if gel discs prepared by mechanical compaction (at 3000 psi pressure, C-discs) is superior to that of discs prepared by regular manual compaction (M-discs) for the release of VCM and EM (10 wt.%). Data demonstrated a significant reduction of burst release of VCM and EM in C-discs (1.8% and 5%, respectively) as compared to that from M-discs within 72 hr (55% and 60%, respectively, p

There is renewed interest in novel spectroscopic techniques for molecular interrogation. Inelastic light scattering techniques can provide real-time phenotypic identification of tissue and cellular state. Here we review Raman spectroscopy as a powerful technique for the identification of cancerous tissue and tumor boundaries.

The uneven morphology and the trapped charges at the surface of the traditionally used supporting substrate-based 2D biosensors produces a scattering phenomenon, which leads to irregular signal from individually fabricated device. Though suspended 2D channel material has the potential to overcome scattering effects from the substrates but achieving reliability and selectivity, have been limiting the biosensor technology. Here, we have demonstrated nanogap electrodes fabrication by using the self-assembly technique, which provides suspension to the 2D-MoS2. These nano-spacing electrodes not only give suspension but also provide robust strength to the atomic layer, which remains freestanding after coating of the Hafnium oxide (HfO2) as well as linkers and antibodies. For evaluating the electrical characteristics of suspended MoS2 FET, gating potential was applied through electrolyte on suspended MoS2 transistor, which achieved lower subthreshold swing 70 mV/dec and ON/OFF ratio 107. Afterward, pH detection has demonstrated at room temperature, which shows an impressive sensitivity of ∼880 by changing 1 unit of pH. Besides, we have successfully shown Escherichia coli (E. coli) bacteria sensing from suspended MoS2 transistor by functionalizing dielectric layer with E. coli antibodies. The reported biosensor has shown the ∼9% of conductance changes with a lower concentration of E. coli (10 CFU/mL; colony-forming unit per mL) as well as maintain the constant sensitivity in three fabricated devices. This type of the architecture has a potential to detect range of biomolecules such as COVID-19 viruses also by altering the oxide surface., Highlights • A suspended MoS2 atomic layer field-effect transistors is reported. • Self-assembled nanogap electrodes provide remarkable robust strength to the MoS2 atomic layer. • Suspended MoS2 field-effect transistor device exhibits impressive pH sensitivity and Escherichia coli bacteria detection. • The sensing mechanism highly selective to Escherichia coli bacteria.

Background Clostridium difficile infection (CDI) is due to the effects of toxins, toxin A and toxin B on the host. Severe CDI is associated with systemic signs of infection. Animal models of CDI demonstrate a strong correlation between systemic toxemia and the occurrence of severe disease. However, current technologies have low sensitivity to detect C difficile toxemia in human subjects. Raman spectroscopy (RS) is an upcoming technology that is used to detect bacteria and their toxins. We speculate that RS may be a sensitive method to detect clinically relevant concentrations of C difficile toxins in serum. Materials and methods Serum samples were spiked with varying concentrations of toxin A, toxin B, and both. RS was performed on an air-dried serum drop that was placed on a mirror-polished stainless steel slide. Raman spectra were obtained, background corrected, vector normalized, and analyzed by Partial Least Square Linear Discriminant Analysis and Support Vector Machine for Classification. Model accuracy was measured by cross-validation and bootstrap methods. Results Toxin-spiked sera of various concentrations (1 ng/mL, 1 pg/mL, and 0.1 pg/mL) were distinguished from control serum 100% with cross-validation error rate ranging from 0% to 18% and bootstrap error rate ranging from 0% to 12% for various concentrations. The sensitivity ranged from 87% to 100% and specificity ranged from 77% to 100% for various concentrations of toxin-spiked serum. Conclusions We conclude that RS may be a sensitive method to detect clinically relevant concentrations of C difficile toxins in serum and thus to help diagnose severe CDI in patients in real-time at the point of care.

Novel approaches toward understanding the evolution of disease can lead to the discovery of biomarkers that will enable better management of disease progression and improve prognostic evaluation. Raman spectroscopy is a promising investigative and diagnostic tool that can assist in uncovering the molecular basis of disease and provide objective, quantifiable molecular information for diagnosis and treatment evaluation. This technique probes molecular vibrations/rotations associated with chemical bonds in a sample to obtain information on molecular structure, composition, and intermolecular interactions. Raman scattering occurs when light interacts with a molecular vibration/rotation and a change in polarizability takes place during molecular motion. This results in light being scattered at an optical frequency shifted (up or down) from the incident light. By monitoring the intensity profile of the inelastically scattered light as a function of frequency, the unique spectroscopic fingerprint of a tissue sample is obtained. Since each sample has a unique composition, the spectroscopic profile arising from Raman-active functional groups of nucleic acids, proteins, lipids, and carbohydrates allows for the evaluation, characterization, and discrimination of tissue type. This review provides an overview of the theory of Raman spectroscopy, instrumentation used for measurement, and variation of Raman spectroscopic techniques for clinical applications in cancer, including detection of brain, ovarian, breast, prostate, and pancreatic cancers and circulating tumor cells.

There is renewed interest in novel spectroscopic techniques for molecular interrogation. Inelastic light scattering techniques can provide real-time phenotypic identification of tissue and cellular state. Here we review Raman spectroscopy as a powerful technique for the identification of cancerous tissue and tumor boundaries.

Background Clinical practice guidelines define Clostridium difficile infections (CDI) as diarrhea (≥3 unformed stools in 24 h) with either a positive C difficile stool test or detection of pseudomembranous colitis. Diagnostic modalities such as toxigenic culture and nucleic acid amplification testing can identify the presence of toxigenic C difficile in stools. But these tests are confounded by the presence of asymptomatic colonization of toxigenic C difficile and lead to overdiagnosis of CDI. The presence of two large toxins, toxin A and B (TcdA and TcdB) is necessary for pathogenicity. Detection of toxins using toxin enzyme immunoassay is difficult as it has low sensitivity and moderate specificity. Raman spectroscopy (RS) is a novel technology that is used to detect bacteria and their toxins. RS does not require any reagents for detection such as antibodies, enzymes, primers, or stains. We hypothesize that RS is a sensitive method to detect C difficile toxins in stool and will solve the problem of overdiagnosis of CDI. Materials and methods CDI negative stool samples were spiked with concentrations (1 ng/mL, 100 pg/mL, 1 pg/mL, and 0.1 pg/mL) of TcdA and TcdB. RS was performed on air-dried smeared samples of stool supernatant on a mirror-polished stainless-steel slide. As RS of feces is difficult because of confounding background material and autofluorescence, samples were photo-bleached before spectral acquisition to reduce autofluorescence. Raman spectra were obtained, background corrected, and vector normalized. The data were split into training (70%) and test (30%) datasets. The machine learning methods used on the training data set were Support Vector Machine with Linear and Radial Kernels, Random Forest, Stochastic Gradient Boosting Machine, and Principle Component Analysis—Linear Discriminant Analysis. Results were validated using a test data set. The best model was chosen, and its accuracy, sensitivity, and specificity were determined. Results In our preliminary results, at all concentrations (1 ng/mL, 100 pg/mL, 1 pg/mL, and 0.1 pg/mL), TcdA or TcdB spiked stool was distinguished from unspiked stool by all models with accuracies ranging from 64% to 77%. Gradient Boosting Machine, Principle Component Analysis—Linear Discriminant Analysis, and Support Vector Machine Linear Kernel performed best with sensitivities ranging from 69% to 90% and specificities ranging from 43% to 78%. Conclusions Using RS, we successfully detected TcdA and TcdB in stool samples albeit with moderate-to-high sensitivity and low-to-moderate specificity. Sensitivity and specificity could be further increased with the implementation of deep learning methods, which require large sample sizes. In terms of sensitivity, RS performs better than toxin enzyme immunoassay and has the potential to rapidly detect C difficile toxins in stool at clinically relevant concentrations and thereby help mitigate overdiagnosis of CDI.

Influenza virus mutates quickly and unpredictably creating emerging pathogenic strains that are difficult to detect, diagnose, and characterize. Conventional tools to study and characterize virus, such as next generation sequencing, genome amplification (RT-PCR), and serological antibody testing, are not adequately suited to rapidly mutating pathogens like Influenza virus where the success of infection heavily depends on the phenotypic expression of surface glycoproteins. Bridging the gap between genome and pathogenic expression remains a challenge. Using sialic acid as a universal Influenza virus binding receptor, a novel virus avidin-biotin complex-based capture coating was developed and characterized that may be used to create future diagnostic and interrogation platforms for viable whole Influenza virus. First, fluorescent FITC probe studies were used to optimize coating component concentrations. Then atomic force microscopy (AFM) was used to profile the surface characteristics of the novel capture coating, acquire topographical imaging of Influenza particles immobilized by the coating, and calculate the capture efficiency of the coating (over 90%) for all four representative human Influenza virus strains tested.

Better knowledge of the breast tumor microenvironment is required for surgical resection and understanding the processes of tumor development. Raman spectroscopy is a promising tool that can assist in uncovering the molecular basis of disease and provide quantifiable molecular information for diagnosis and treatment evaluation. In this work, eighty-eight frozen breast tissue sections, including forty-four normal and forty-four tumor sections, were mapped in their entirety using a 250-μm-square measurement grid. Two or more smaller regions of interest within each tissue were additionally mapped using a 25 μm-square step size. A deep learning algorithm, convolutional neural network (CNN), was developed to distinguish histopathologic features with-in individual and across multiple tissue sections. Cancerous breast tissue were discriminated from normal breast tissue with 90 % accuracy, 88.8 % sensitivity and 90.8 % specificity with an excellent Area Under the Receiver Operator Curve (AUROC) of 0.96. Features that contributed significantly to the model were identified and used to generate RGB images of the tissue sections. For each grid point (pixel) on a Raman map, color was assigned to intensities at frequencies of 1002 cm−1 (Phenylalanine), 869 cm−1 (Proline, C C stretching of hydroxyproline-collagen assignment, single bond stretching vibrations for the amino acids proline, valine and polysaccharides) and 1309 cm−1 (CH3/CH2 twisting or bending mode of lipids). The Raman images clearly associate with hematoxylin and eosin stained tissue sections and allow clear visualization of boundaries between normal adipose, connective tissue and tumor. We demonstrated that this simple imaging technique allows high-resolution, straightforward molecular interpretation of Raman images. Raman spectroscopy provides rapid, label-free imaging of microscopic features with high accuracy. This method has application as laboratory tool and can assist with intraoperative tissue assessment during Breast Conserving surgery.

Exceptional ion mobility spectrometry mass spectrometry (IMS-MS) developments by von Helden, Jarrold, and Clemmer provided technology that gives a view of chemical/biological compositions previously not achievable. The ionization method of choice used with IMS-MS has been electrospray ionization (ESI). In this special issue contribution, we focus on fundamentals of heretofore unprecedented means for transferring volatile and nonvolatile compounds into gas-phase ions singly and multiply charged. These newer ionization processes frequently lead to different selectivity relative to ESI and, together with IMS-MS, may provide a more comprehensive view of chemical compositions directly from their original environment such as surfaces, e.g., tissue. Similarities of results using solvent- and matrix-assisted ionization are highlighted, as are differences between ESI and the inlet ionization methods, especially with mixtures such as bacterial extracts. Selectivity using different matrices is discussed, as are results which add to our fundamental knowledge of inlet ionization as well as pose additional avenues for inquiry. IMS-MS provides an opportunity for comparison studies relative to ESI and will prove valuable using the new ionization technologies for direct analyses. Our hypothesis is that some ESI-IMS-MS applications will be replaced by the new ionization processes and by understanding mechanistic aspects to aid enhanced source and method developments this will be hastened.

Calcium polyphosphate (CPP) hydrogel is used to load erythromycin (EM) and vancomycin (VCM) by means of two loading methods: they are either added directly to the formed CPP hydrogel (Gel Mixture method) or mixed with CPP powders, followed by the formation of CPP-antibiotic hydrogel (Powder Mixture method). The release of loaded antibiotics from CPP hydrogel is measured up to 48 hr. Compared to Powder Mixture method, Gel Mixture method significantly reduced the burst release of embedded antibiotics. A significant change in CPP hydrogel Raman characteristic peaks is observed only in Gel Mixture method, indicating a close interaction between embedded antibiotics with CPP hydrogel matrix. In contrast, a similarity between characteristic peaks of CPP hydrogel and Powder Mixture method shows that antibiotic incorporation does not interfere with CPP gel formation, resulting in no ionic interaction between antibiotic and polyphosphate chains. Rheometer analysis further confirms that the hydrophobic nature of EM impacts the viscoelastic properties of CPP hydrogel, whereas the hydrophilic VCM exhibits a higher loading efficiency. The potential application of CPP hydrogel as a ceramic matrix for sustained drug release warrants further investigation.

A key part of treatment for brain tumors is tumor resection, the amount of tumor resection has a direct correlation on the mortality of the patient. However, tools available to surgeons to ensure maximal resection while preserving a patient's functional status often increase surgery time or are lacking in accuracy. Raman spectroscopy is a promising modality that can provide real time intraoperative data to the surgeon about whether a tissue is normal or cancerous, thus aiding the surgeon in obtaining maximal safe resection. In this paper, we pair Raman spectroscopy with a supervised machine learning technique, support vector machine, to classify fresh tissue samples as solid tumor, infiltrating tumor, necrosis, or normal brain tissue. The support vector machine classifier resulted in 89% accuracy of the 117 tissue samples while delivering real time results. Accurate real-time tissue characterization will vastly reduce the amount of time a surgeon waits for the results of biopsies and provides a means for intraoperative margin assessment during tumor resection.

In neurosurgical applications, a tool capable of distinguishing grey matter, white matter, and areas of tumor and/or necrosis in near-real time could greatly aid in tumor resection decision making. Raman spectroscopy is a non-destructive spectroscopic technique which provides molecular information about the tissue under examination based on the vibrational properties of the constituent molecules. With careful measurement and data processing, a spatial step and repeat acquisition of Raman spectra can be used to create Raman images. Forty frozen brain tissue sections were imaged in their entirety using a 300-µm-square measurement grid, and two or more regions of interest within each tissue were also imaged using a 25 µm-square step size. Molecular correlates for histologic features of interest were identified within the Raman spectra, and novel imaging algorithms were developed to compare molecular features across multiple tissues. In previous work, the relative concentration of individual biomolecules was imaged. Here, the relative concentrations of 1004, 1300:1344, and 1660 cm(-1), which correspond primarily to protein and lipid content, were simultaneously imaged across all tissues. This provided simple interpretation of boundaries between grey matter, white matter, and diseased tissue, and corresponded with findings from adjacent hematoxylin and eosin-stained sections. This novel, yet simple, multi-channel imaging technique allows clinically-relevant resolution with straightforward molecular interpretation of Raman images not possible by imaging any single peak. This method can be applied to either surgical or laboratory tools for rapid, non-destructive imaging of grey and white matter.

Amorphous calcium polyphosphate (ACPP), an inorganic polymer ceramic, has shown promise as a drug delivery matrix following a repeat gelling protocol. This study described a simple method of preparing ACPP hydrogel in the presence of an excess volume of water. The increased water availability accelerates water molecule ingress and microstructural transformation of ACPP hydrogels. The impact of some experimental settings (soaking time, temperature, stirring, and ACPP particle size) on the physiochemical and rheological natures of ACPP hydrogel were investigated and from which possible hydrogel formation mechanisms were inferred. We believe that the formation of ACPP hydrogel is through the mechanisms of intermolecular ionic interaction and entanglement of polyphosphate chains. The potential application of ACPP hydrogel as a ceramic matrix for sustained drug release warrants further investigation.

Few studies have been reported that focus on developing implant surface nanofiber (NF) coating to prevent infection and enhance osseointegration by local drug release. In this study, coaxial doxycycline (Doxy)-doped polycaprolactone/polyvinyl alcohol (PCL/PVA) NFs were directly deposited on a titanium (Ti) implant surface during electrospinning. The interaction of loaded Doxy with both PVA and PCL NFs was characterized by Raman spectroscopy. The bonding strength of Doxy-doped NF coating on Ti implants was confirmed by a stand single-pass scratch test. The improved implant osseointegration by PCL/PVA NF coatings in vivo was confirmed by scanning electron microscopy, histomorphometry and micro computed tomography (μCT) at 2, 4 and 8 weeks after implantation. The bone contact surface (%) changes of the NF coating group (80%) is significantly higher than that of the no NF group (

Purpose Rapid and reliable methods for conducting biological dosimetry are a necessity in the event of a large-scale nuclear event. Conventional biodosimetry methods lack the speed, portability, ease of use, and low cost required for triaging numerous victims. Here we address this need by showing that polymerase chain reaction (PCR) on a small number of gene transcripts can provide accurate and rapid dosimetry. The low cost and relative ease of PCR compared with existing dosimetry methods suggest that this approach may be useful in mass-casualty triage situations. Methods and Materials Human peripheral blood from 60 adult donors was acutely exposed to cobalt-60 gamma rays at doses of 0 (control) to 10 Gy. mRNA expression levels of 121 selected genes were obtained 0.5, 1, and 2 days after exposure by reverse-transcriptase real-time PCR. Optimal dosimetry at each time point was obtained by stepwise regression of dose received against individual gene transcript expression levels. Results Only 3 to 4 different gene transcripts, ASTN2, CDKN1A, GDF15, and ATM, are needed to explain ≥0.87 of the variance (R 2 ). Receiver-operator characteristics, a measure of sensitivity and specificity, of 0.98 for these statistical models were achieved at each time point. Conclusions The actual and predicted radiation doses agree very closely up to 6 Gy. Dosimetry at 8 and 10 Gy shows some effect of saturation, thereby slightly diminishing the ability to quantify higher exposures. Analyses of these gene transcripts may be advantageous for use in a field-portable device designed to assess exposures in mass casualty situations or in clinical radiation emergencies.

TMDs such as MoS2 is playing an important role in the field of FETs, photodetectors, thin film transistors and efficient biosensors because of their direct band-gap, high mobility, and biocompatibility. Despite these strengths, the performance and reliability of such atomic layer are easily influenced by supporting substrate. Interaction between the supporting substrate and MoS2 implies that interface control is vital for performance of devices consisting of monolayer MoS2. In particular, the Silicon dioxide (SiO2) supporting substrate has an uneven morphology and is chemically active because of trapped environmental gases, unknown functional groups, chemical adsorbates, and charges. Thus, adding another layer of MoS2 on the top of SiO2 cannot contribute charge transport clearly, which leads to the unreliable function of every single device. To solve the interface problem, suspended 2D layer devices have been reported by wet etching silicon di oxide underneath the monolayer. Freestanding MoS2 has shown 10 times greater back gate electronic mobility than the supporting on the SiO2 substrate, which is ~0.9 cm2/Vs [1]. However, the existing SiO2 requires hazardous chemical etchants such as hydrofluoric acid (HF), which is difficult to handle and affects the 2D film structure and purity [2]. Secondly, freestanding MoS2 sags between the two electrodes because of the high spacing (~ 2 µm), which makes it impossible to coat another layer such as hafnium oxide (HfO2) and antibodies on top of monolayer. Therefore, this structure impedes making top gate FET biosensors, which allows for only back gating. However, back gate mobility is far lesser than the top gate mobility which hinders making a highly sensitive FET-based biosensor because the sensitivity of a sensor depends on its mobility [3]. Moreover, when linkers/antibodies are directly attached to the bare channel, the transduction mechanism is the combination of the electrostatic gating, direct charge transfer and mobility modulation. Therefore, it is desirable to eliminate the density of defects by covering the bare channel material with insulating material and then functionalizing linkers and antibodies on the top of the insulator [3, 4]. In this work, CVD grown MoS2 channel material is transferred on self-assembled photolithographically patterned nano-gaps to achieve suspension and is covered with HfO2 to eliminate the direct functionalization of channel material. These nano-gap arrays provide mechanical strength to the monolayer and do not allow the supporting substrate to touch after coating another thin insulating layer as well as linkers/antibodies. HfO2 can be easily functionalized by linkers (Benzene 1, 4 dithiols) and antibodies (E-coli antibodies) to bring variation to the suspended 2D material by targeting a charged biomolecule (E-coli). In addition, termination of the supporting substrate leads to increments of electron mobility which are directly proportional to the sensitivity of the FET biosensor. The proposed FET biosensor has the capability to detect one molecule because of its single atomic layer as a channel material, its scalability due to the involvement of optical photolithography, and its fast response because of higher mobility. References Jin, T., et al., Suspended single-layer MoS2 devices. Journal of Applied Physics, 2013. 114(16): p. 164509. Zhang, F., et al., Etchant-free transfer of 2D nanostructures. Nanotechnology, 2017. 29(2): p. 025602. Sarkar, D., et al., MoS2 field-effect transistor for next-generation label-free biosensors. ACS nano, 2014. 8(4): p. 3992-4003. Kalantar-zadeh, K. and J.Z. Ou, Biosensors based on two-dimensional MoS2. ACS Sensors, 2015. 1(1): p. 5-16.

The long-term effect of chronically implanted electrodes is the formation of a glial scar. Therefore, it is imperative to assess the biocompatibility of materials before employing them in neural electrode fabrication. Platinum alloy and iridium oxide have been identified as good candidates as neural electrode biomaterials due to their mechanical and electrical properties, however, effect of glial scar formation for these two materials is lacking. In this study, we applied a glial scarring assay to observe the cellular reactivity to platinum alloy and iridium oxide wires in order to assess the biocompatibility based on previously defined characteristics. Through real-time PCR, immunostaining and imaging techniques, we will advance the understanding of the biocompatibility of these materials. Results of this study demonstrate iridium oxide wires exhibited a more significant reactive response as compared to platinum alloy wires. Cells cultured with platinum alloy wires had less GFAP gene expression, lower average GFAP intensity, and smaller glial scar thickness. Collectively, these results indicated that platinum alloy wires were more biocompatible than the iridium oxide wires.

Surgical excision of brain tumors provides a means of cytoreduction and diagnosis while minimizing neurologic deficit and improving overall survival. Despite advances in functional and three-dimensional stereotactic navigation and intraoperative magnetic resonance imaging, delineating tissue in real time with physiological confirmation is challenging. Raman spectroscopy is a promising investigative and diagnostic tool for neurosurgery, which provides rapid, non-destructive molecular characterization in vivo or in vitro for biopsy, margin assessment, or laboratory uses. The Raman Effect occurs when light temporarily changes a bond’s polarizability, causing change in the vibrational frequency, with a corresponding change in energy/wavelength of the scattered photon. The recorded inelastic scattering results in a “fingerprint” or Raman spectrum of the constituent under investigation. The amount, location, and intensity of peaks in the fingerprint vary based on the amount of vibrational bonds in a molecule and their ensemble interactions with each other. Distinct differences between various pathologic conditions are shown as different intensities of the same peak, or shifting of a peak based on the binding conformation. Raman spectroscopy has potential for integration into clinical practice, particularly in distinguishing normal and diseased tissue as an adjunct to standard pathologic diagnosis. Further, development of fiber-optic Raman probes that fit through the instrument port of a standard endoscope now allows researchers and clinicians to utilize spectroscopic information for evaluation of in vivo tissue. This review highlights the need for such an instrument, summarizes neurosurgical Raman work performed to date, and discusses the future applications of neurosurgical Raman spectroscopy.

An array of design strategies have been targeted toward minimizing failure of implanted microelectrodes by minimizing the chronic glial scar around the microelectrode under chronic conditions. Current approaches toward inhibiting the initiation of glial scarring range from altering the geometry, roughness, size, shape, and materials of the device. Studies have shown materials which mimic the nanotopography of the natural environment in vivo will consequently result in an improved biocompatible response. Nanofabrication of electrode arrays is being pursued in the field of neuronal electrophysiology to increase sampling capabilities. Literature shows a gap in research of nanotopography influence in the reduction of astrogliosis. The aim of this study was to determine optimal feature sizes for neural electrode fabrication, which was defined as eliciting a nonreactive astrocytic response. Nanopatterned surfaces were fabricated with nanoimprint lithography on poly(methyl methacrylate) surfaces. The rate of protein adsorption, quantity of protein adsorption, cell alignment, morphology, adhesion, proliferation, viability, and gene expression was compared between nanopatterned surfaces of different dimensions and non-nanopatterned control surfaces. Results of this study revealed that 3600 nanopatterned surfaces elicited less of a response when compared with the other patterned and non-nanopatterned surfaces. The surface instigated cell alignment along the nanopattern, less protein adsorption, less cell adhesion, proliferation and viability, inhibition of glial fibrillary acidic protein, and mitogen-activated protein kinase kinase 1 compared with all other substrates tested. © 2012 Wiley Periodicals, Inc. J Biomed Mater Res Part A, 2013.

In a large-scale nuclear incident, many thousands of people may be exposed to a wide range of radiation doses. Rapid biological dosimetry will be required on an individualized basis to estimate the exposures and to make treatment decisions. To ameliorate the adverse effects of exposure, victims may be treated with one or more cytokine growth factors, including granulocyte colony-stimulating factor (G-CSF), which has therapeutic efficacy for treating radiation-induced bone marrow ablation by stimulating granulopoiesis. The existence of infections and the administration of G-CSF each may confound the ability to achieve reliable dosimetry by gene expression analysis. In this study, C57BL/6 mice were used to determine the extent to which G-CSF and lipopolysaccharide (LPS, which simulates infection by gram-negative bacteria) alter the expression of genes that are either radiation-responsive or non-responsive, i.e., show potential for use as endogenous controls. Mice were acutely exposed to (60)Co γ rays at either 0 Gy or 6 Gy. Two hours later the animals were injected with either 0.1 mg/kg of G-CSF or 0.3 mg/kg of LPS. Expression levels of 96 different gene targets were evaluated in peripheral blood after an additional 4 or 24 h using real-time quantitative PCR. The results indicate that the expression levels of some genes are altered by LPS, but altered expression after G-CSF treatment was generally not observed. The expression levels of many genes therefore retain utility for biological dosimetry or as endogenous controls. These data suggest that PCR-based quantitative gene expression analyses may have utility in radiation biodosimetry in humans even in the presence of an infection or after treatment with G-CSF.

Neural electrode devices hold great promise to help people with the restoration of lost functions. However, research is lacking in the biomaterial design of a stable, long-term device. Glial scarring is initiated when a device is inserted into brain tissue and an inflammatory response ensues. Astrocytes become hypertrophic, hyperplastic, and upregulate glial-fibrillary acidic protein. This study was designed to investigate the astrocyte proliferation, viability, morphology, and gene expression to assess the reactive state of the cells on different material surfaces. Although platinum and silicon have been extensively characterized both in vivo and in vitro for their biocompatibility with neuronal cells, this study used the novel usage of PMMA and SU-8 in neural electrodes by comparative analysis of materials' biocompatibility. This study has shown evidence of noncytotoxicity of SU-8. We have also confirmed the biocompatibility of PMMA with astrocytes. Moreover, we have established sound guidelines of which neural implant materials should meet to be depicted biocompatible.

Fabrication of microfluidic systems capable of extracting and isolating nucleic acids from biological samples and preparing them for downstream applications within the same device is of interest as on-chip sample preparation reduces the time and effort expended on multi-step benchtop procedures. A microfluidic chip capable of cell lysis, nucleic acid extraction and immobilization has been developed in our laboratory. This report focuses on substrate development and chip integration of the nucleic acid immobilization platform. The immobilization region was initially developed using poly-adenylated mRNA released from normal human lymphoblastoid cells. After immobilization, the mRNA remains functional for amplification by the reverse transcription polymerase chain reaction (RT-PCR) and quantitative real-time PCR (qPCR) gene expression analyses. Detailed surface functionalization, chemical modification, and covalent oligonucleotide immobilization methods are described. Vapor and liquid deposition techniques for Pyrex functionalization by 10-(carbomethoxy)decyl-dimethylchlorosilane (CMDCS) were developed and an optimal method was determined for microfluidic chip application. CMDCS substrate depositions and modification were characterized by atomic force microscopy and contact angle goniometry, respectively. Oligonucleotide immobilizations and mRNA bindings were determined by fluorescence microscopy. Functional, selective platform integration within the microfluidic chip was confirmed by standard RT-PCR and qPCR systems.

This paper presents a design guideline for a piezoelectric actuated check valve diaphragm micropump for microfluidic applications. Diaphragm average displacement was adopted in analyzing a piezoelectrically actuated diaphragm. For the first time, the relationship between the stroke volume and backpressure of a check valve diaphragm micropump were simulated with a Finite Element Analysis (FEA) tool. The simulated results reasonably agreed to the experimental results of the micropump.

Thin film materials are widely used in the fabrication of semiconductor microelectronic devices. In thin film deposition, cleanliness of substrate surface have become critically important as over 50% of yield losses in integrated circuit fabrication are caused by microcontamination [1] . There are many wafer cleaning techniques. The most successful approach for silicon wafer cleaning technique is RCA clean [2] . But for glass substrate it is still not known which procedure of cleaning is the best. This paper provides an understanding of the right way of glass wafer cleaning method, with a focus towards identifying good bond strength. Two wafer cleaning techniques have been used for cleaning glass substrates in the context of laser micro-joining of dissimilar substrates. First cleaning procedure involves two steps, first cleaning in acetone solution and then in DI water solution. After each step dried with N2. Second cleaning procedure involves four steps, first cleaning with 1% Alconox solution, second in DI water, third in acetone solution and finally in a methanol solution and dried with N2 after each step. Deposition of Ti thin film on top of these two types of substrate using DC magnetron sputtering method also showed better adhesion of Ti film on glass for the second type of cleaning method. Scanning electron microscopy (SEM) analyses of the lap shear tested failed surfaces for these two kinds of samples revealed strong bond for samples prepared by second cleaning method compared to first cleaning method. Characterization of these two sets of samples using X-ray photoelectron spectroscopy (XPS) has shown excellent contamination removal for the second cleaning method. This modification is believed to be due to reduction of carbon contamination.

INTRODUCTION: Raman spectroscopy is a tool that utilizes a non-contact label-free modality of optical imaging that measures inelastic scattered photon shifts to give a unique biochemical signature. There is established work showing that these unique fingerprints can differentiate a glioma from necrosis and normal brain. The ability to instantly characterize these organic tissues intraoperatively, then, can help guide a surgeon’s resection. The goal of the present study is to review the Raman work that has been performed to date, its demonstrated safety in a rat model and the indications for use of this operative tool. METHODS: We review the fundamental principles of Raman spectroscopy, some contemporary data, and show its effectiveness as an intraoperative probe. Because the probe uses a 100mW 785nM laser wavelength, we also determined the threshold at which it causes damage to cortical grey matter in a rat model. RESULTS: Raman spectroscopy has a high sensitivity and specificity (>97%) when discriminating between grey matter, necrosis and GBM. A discriminant function analysis, supervised classification algorithm, is used for spectral identification to allow relevant spectral interpretation and allows for tailoring to which Raman peaks are significant for diagnosis. In regards to safety, animal experiments showed no damage seen at 10 seconds/250mW and estimated damage to occur at 60 seconds/250mW. We also present an intraoperative workflow of how this tool could be used in the operating room. CONCLUSION: A Raman spectrographic probe is a safe and powerful tool that can provide live intraoperative diagnosis and identify tissue margins. Further work is being done to identify clinical outcomes, the unique fingerprints of other pathological tissues and further differentiate gliomas based on molecular markers like IDH-1.

Electron beam evaporation (EB-PVD) and cathodic arc physical vapor deposition (CA-PVD) techniques were used for the preparation of titanium (Ti) thin films onto Pyrex borosilicate 7740 glass wafers and the deposited films were characterized by X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM) techniques. The microstructure and surface morphology of the films were studied as a function of the film deposition techniques. Film properties such as, adherence, microstructure and roughness were interconnected to the laser joint strength between Ti coated glass wafers and polyimide films. Ti thin films on glass had a natural oxide layer on the surface as found from XPS. AFM study showed the formation of a uniform Ti coating consisted of packed crystallites with average size of 35 nm by EB-PVD. The root-mean-square surface roughness of the films was 1–2 nm. Whereas, films prepared by CA-PVD had crystallites with an average size of 120 nm and defects in the form of macro-particles which is a common attribute of this deposition system. The surface roughness of the film was 125 nm. The laser joint strength was found to be influenced by the Ti film quality on the glass substrate.

Acute rejection (AR) remains problematic in renal transplantation. As a marker, serum creatinine is limited, warranting a more effective screening tool. Raman spectroscopy (RS) can detect T-cell activation with high sensitivity. In this study we explore its specificity. Seventy-five inactivated, 40 alloantigen-activated, and 75 CD3/CD28-activated T-cells were analyzed using RS. CD3/CD28-activated peak magnitudes (PM) were 4.3% to 23.9% lower than Inactivated PM at positions: 903cm−1, 1031cm−1, 1069cm−1, 1093cm−1, 1155cm−1, 1326cm−1, and 1449cm−1, with a difference in peak ratio (PR) observed at the 1182:1195cm−1 position (0.91 ± 0.06 vs. 1.2 ± 0.01, respectively: p = 0.006). Differences in CD3/CD28- and alloantigen-activated PM were observed at: 903cm−1, 1031cm−1, 1093cm−1, 1155cm−1, 1326cm−1, and 1449cm−1, with no PR differences at the 1182:1195cm−1 position (0.91 ± 0.06 vs. 0.86 ± 0.09: p = 0.8). Spectral signature separation of CD3/CD28 - and alloantigen-activated groups was 100% specific and sensitive. We conclude that RS can differentiate T-cells activated by different stimuli with high sensitivity and specificity.

Probes are the interface between microsystems and bio-cells. The ideal interface is one-to-one interface. Though various research groups have been able to establish some sort of interfaces after many years of research, they are very crude. Neurons are millions in numbers, whereas the prostheses successfully built so far have only a few hundred probes at best. Creating an effective interface is still far away. Though we have micro- and nano-technologies, we couldn't build a prosthesis with an effective resolution. Main reasons behind it are the type of probe being used and the poor design of the probe. To address this problem, we developed a methodology to design a probe and an array of probes with better resolution and less resistive donut probe. This methodology helps us to design a probe optimizing all the parameters. We presented our methodology through a design that is capable of 70 μm penetration inside the tissue. The tissue heating by our designed probe is only 0.411 UC. We also characterized the donut probe, which could be used by any research group to design a donut probe of their specific need.

Teflon ® FEP (fluorinated ethylene propylene) is resistant to most chemical solvents, is heat sealable and has low moisture uptake, which make this polymer attractive as a packaging materials for electronics and implantable devices. Teflon ® FEP/Ti microjoints were fabricated by using focused infrared laser irradiation. Teflon ® FEP/Ti interfaces were studied by using X-ray photoelectron spectroscopy (XPS), Auger electron spectroscopy (AES) and scanning electron microscopy coupled with energy dispersive spectroscopy (SEM–EDS). The XPS results give evidence for the formation of Ti–F bonds in the interfacial region. The AES and SEM–EDS results show that the chemical bond formation occurs only in the actual bond area. No evidence for chemical bond formation was found in the heat affected zone surrounding the laser bonds.

Kapton® FN and Teflon® FEP (fluorinated ethylene propylene) polymers are resistant to most chemical solvents, heat sealable, and have low moisture uptake, which make them attractive as packaging materials for electronics and implantable devices. Kapton® FN/Ti and Teflon® FEP/Ti microjoints were fabricated by using focused infrared laser irradiation. Laser-bonded samples were tested with a micro-testing machine under lap shear load and the bond strength was determined. The bond strength for the Kapton® FN/Ti and Teflon® FEP/Ti systems was found to be 3.32 and 8.48 N/mm(2), respectively. The failure mode of the mechanically tested samples was studied by using optical microscopy and scanning electron microscopy coupled with energy dispersive X-ray spectroscopy. Chemical interactions during laser bonding of Kapton® FN to titanium were studied by using X-ray photoelectron spectroscopy (XPS). The XPS results give evidence for the formation of Ti-F bonds in the interfacial region.

Acute rejection (AR) remains a significant complication in renal transplant patients. Using serum creatinine for AR screening has proven problematic, and thus a noninvasive, highly sensitive and specific test is needed. T cells from human peripheral blood were analyzed using Raman spectroscopy. Fifty-one Mixed Lymphocyte Culture (MLC) activated T cells (ATC), 28 Mitomycin C inactivated T cells (ITC), and 35 resting T cells (RTC), were studied utilizing 785 and 514.5 nm wavelengths. Statistical analysis following subtraction of fluorescence used Student's t test to quantify peak ratio differences and discriminant function analysis (DFA), with three distinct sectors assigned for grouping purposes: Sector I, ITC; Sector II, ATC; Sector III, RTC. Differences between ATC and non-activated T cells (ITC and RTC) were found at 1182 and 1195 cm-1 peak positions for both wavelengths. Significant differences in peak ratios for 785 and 514.5 nm wavelengths existed between ATC and RTC ( p = 0.001 and p = 0.006, respectively) and ATC and ITC ( p = 0.001 and p = 0.001, respectively), with a trend in differences observed between ITC and RTC ( p = 0.07 and p = 0.08, respectively). Analysis of the DFA-derived sector distribution for the 785 and 514.5 nm wavelengths revealed a sensitivity of 95.7% and 89.3%, respectively, and a specificity of 100% and 93.8%, respectively. This data suggests that Raman spectroscopy can detect significant differences between activated and nonactivated T cells based upon cell-surface receptor expression, thereby establishing unique signatures that can aid in the development of a noninvasive AR screening tool with high sensitivity and specificity.

Ten samples of crystalline aluminum nitride (AlN) film were deposited on sapphire and silicon substrates by a plasma source molecular beam method. The samples were analyzed using X-ray photoelectron spectroscopy (XPS) depth profiling and high-resolution X-ray diffraction. Oxygen levels were observed to decrease exponentially from the surface into the bulk film. Aluminum, nitrogen and oxygen peaks were fitted with subpeaks in a consistent manner and the subpeaks were assigned to chemical states. AlN subpeaks were observed at 73.5 eV for Al2p and 396.4 eV for N1s. An N1s subpeak at 395.0 eV was assigned to NN defects. No direct NO bonds are assigned; rather it is proposed that an NAlO bond sequence is the source of higher binding energy N1s subpeaks. The observations in this study support a model in which oxygen is bound only to aluminum in the form of AlO octahedral complexes dispersed or clustered throughout the main AlN matrix or as AlO bonds on the crystal grain boundaries. The data also suggest that the AlN lattice parameters are related to oxygen content, since the c-axis is observed to increase with increasing oxygen content. Copyright © 2008 John Wiley & Sons, Ltd.

Technical advances in the application of laparoscopic and robotic surgical systems have improved platform usability. The authors hypothesized that using two monitors instead of one would lead to faster performance with fewer errors. All tasks were performed using a surgical robot in a training box. One of the monitors was a standard camera with two preset zoom levels (zoomed in and zoomed out, single-monitor condition). The second monitor provided a static panoramic view of the whole surgical field. The standard camera was static at the zoomed-in level for the dual-monitor condition of the study. The study had two groups of participants: 4 surgeons proficient in both robotic and advanced laparoscopic skills and 10 lay persons (nonsurgeons) who were given adequate time to train and familiarize themselves with the equipment. Running a 50-cm rope was the basic task. Advanced tasks included running a suture through predetermined points and intracorporeal knot tying with 3–0 silk. Trial completion times and errors, categorized into three groups (orientation, precision, and task), were recorded. The trial completion times for all the tasks, basic and advanced, in the two groups were not significantly different. Fewer orientation errors occurred in the nonsurgeon group during knot tying (p = 0.03) and in both groups during suturing (p = 0.0002) in the dual-monitor arm of the study. Differences in precision and task error were not significant. Using two camera views helps both surgeons and lay persons perform complex tasks with fewer errors. These results may be due to better awareness of the surgical field with regard to the location of the instruments, leading to better field orientation. This display setup has potential for use in complex minimally invasive surgeries such as esophagectomy and gastric bypass. This technique also would be applicable to open microsurgery.

Amorphous and crystalline iridium oxide thin films with potential use as coating materials for stimulation electrodes were studied. Characterization of these films by cyclic voltammetry and impedance spectroscopy has revealed a considerable decrease in impedance and an increase in charge capacity of iridium oxide thin films after an electrochemical activation process in 0.9% NaCl solution. The surface morphology of these films was studied by scanning electron microscopy. The two types of IrO 2 films were also compared under conditions relevant to applications as stimulation electrodes. The results indicate that amorphous IrO 2 films have significantly higher charge storage capacity and lower impedance than crystalline IrO 2 films. This makes the amorphous films a preferable coating material for stimulation applications.

Performance of a conventional phase detector implemented using analog circuitry is affected by, among other factors, the parameter value drifting of the analog components with environment (e.g., temperature) and time (i.e., aging). It is also adversely impacted by electromagnetic interferences likely existing in the analog circuits when the detector operates in a high frequency range. More importantly, such a detector is inflexible to compensate various nonlinear characteristics of sensors and is very difficult to realize sophisticated signal processing strategies desired for practical applications. To address issues like these, we have developed a digital system approach that uses the zero-crossing algorithm for phase detection. The phase detection limit and dynamic phase response of the system were assessed using surface acoustic wave (SAW) sensors. Our preliminary evaluation involved aluminum nitride (AlN) dual-mode differential sensors, which were fabricated on an AlN ( 0 0 0 1 ) / A l 2 O 3 ( 1 1 2 ¯ 0 ) thin film structure, with the SAW and shear horizontal SAW (SH-SAW) operating at approximately 243 MHz and 256 MHz, respectively. Due to the hardware constraints, the digital phase processing was carried out in an off-line fashion. Our baseline experiments without sensor indicate that the system can achieve a lower level of phase noise with the standard deviation being about 0.005°. Experiments with the differential sensors running in the SAW and SH-SAW modes exhibit that the system can reach a phase detection limit of 0.02°. The differential system showed small temperature coefficient at ppm level measured by varying the sensor temperature using a thermal control oven. Finally, our use of the system in measuring the response of the SH-SAW sensor to sodium chloride (NaCl) solution conductivity shows that the system is capable of performing microanalysis of liquid properties. We conclude that a real-time fully digital phase detection system can be practically achieved.

Phages are promising alternatives to antibodies as the biorecognition element in a variety of biosensing applications. In this study, a monolayer of bacteriophage P22 whose tailspike proteins specifically recognize Salmonella serotypes was covalently bound to glass substrates through a bifunctional cross linker 3-aminopropyltrimethoxysilane. The specific binding of Salmonella typhimurium to the phage monolayer was studied by enzyme-linked immunosorbent assay and atomic force microscopy. Escherichia coli and a Gram-positive bacterium Listeria monocytogenes were also studied as control bacteria. The P22 particles show strong binding affinity to Salmonella typhimurium. In addition, the dried P22 monolayer maintained 50% binding capacity to Salmonella typhimurium after a one-week storage time. This is a promising method to prepare phage monolayer coatings on surface plasmon resonance and acoustic biosensor substrates in order to utilize the nascent phage display technology.

The possibility of using surface topography for guidance of different biological molecules and cells is a relevant topic that can be applied to a wide research activity. This study investigated the adsorption of fibronectin to a diffraction grated silicon surface. The rectangular grating profile featured a controlled surface with 350 nm period and a corrugation depth of 90 nm. Results demonstrated that the controlled surface had a significantly positive effect on the fibronectin binding. Thus, nanoscale surface topography can enhance fibronectin binding.

The electrical response of a hydrogen-sensing device is either a rectifying diode-type or a capacitor-type but could not be operated simultaneously in both the modes. However, we are able to demonstrate that a Pd/AlN/SiC device can operate in dual mode either as a rectifying diode or a capacitor. The device with a 50 nm AlN layer shows a shift of ∼0.35 V for 100 ppm H 2 in both the modes, at a temperature of 150 °C. It seems that the presence of donor levels in the bandgap of the AlN layer with a wide range of energy is responsible for the observed electrical behavior of this device.

The immobilization of antibodies to sensor surfaces is critical in biochemical sensor development. In this study, Poly(ethylene glycol) (PEG) and Jeffamine spacers were employed to tether Escherichia coli K99 pilus antibody to silicon wafer surfaces for the purpose of improving the orientation of antibody as well as reducing the steric hindrance. To illustrate the effect of spacer length, a variety of linear polymers were used to covalently attach the antibodies to silicon surfaces. Atomic Force Microscopy (AFM) and X-ray photoelectron spectroscopy (XPS) were used to characterize the surface morphology and chemical composition at each reaction step. The effect of spacer length in improving the specificity of immobilized antibody was investigated by attaching E. coli on the end of an AFM tip. The distribution of unbinding force and rupture distance from the force-distance curves obtained by AFM showed that the introduction of PEG spacer facilitates bacterial recognition which can improve the incidence of interactions by up to 90%. J600 proved to be the most effective spacer overcoming the steric hindrance seen with direct immobilization of antibody. In addition, the force spectroscopy reveals the elementary force quantum of E. coli-antibody to be 0.3 nN.

The in vivo biocompatibility of pure sapphire and borosilicate glass (BSG) implanted onto the cerebral cortex was studied via magnetic resonance imaging (MRI) and histopathology. Each implant was embedded onto the cortical surface of an adult rat brain for a total of 28 days. Rats underwent surgery with and without implants, and rats with purposely damaged cortical implant sites were also studied. Each animal was imaged via MRI before surgery as well as 10 and 28 days after the surgery. Histopathological results of animals were obtained on the 28th day to determine the specific effect on neurons. Despite the fact that sapphire has been widely used in a variety of medical implants, both MRI and histopathological results indicate that pure sapphire is not biocompatible with the cerebral cortex. On the contrary, BSG implants appear to be biocompatible with the cortical surface.